This invention relates to defibrillators, particularly semi-automatic and automatic external defibrillators, and communication networks for transferring information to and from defibrillators on the networks. The invention also relates to methods of operating and maintaining defibrillators in communication networks.
One frequent consequence of heart attacks is the development of cardiac arrest associated with a heart arrhythmia, such as ventricular fibrillation. Ventricular fibrillation may be treated by applying an electric shock to the patient's heart through the use of a defibrillator. Cardiopulmonary resuscitation (CPR) is commonly used to treat victims of cardiac arrest until a defibrillator can be brought to bear on the victim's arrhythmia.
The chances of surviving a cardiac arrest decrease with time after the attack. Quick response to an arrest by performing CPR and/or by administering a defibrillating shock is therefore of critical importance. The American Heart Association's "Chain of Survival" recites the following steps:
1. Rapid access to medical care, such as by activating an emergency response system (e.g., calling an ambulance); PA1 2. Rapid CPR initiated by a bystander or other early caregiver to help the victim survive until more advanced care arrives; PA1 3. Rapid defibrillation; and PA1 4. Rapid application of Advanced Cardiac Life Support (ACLS), such as airway management, drugs, etc. The benefits of this approach are discussed in more detail in Cummins, et al., "Improving Survival From Sudden Cardiac Arrest: The `Chain of Survival` Concept," 83 Circulation 1832-47 (May 1991).
Physicians have suggested keeping a cellular telephone, radio or other communication device with defibrillators so that medical help can be summoned near the time that treatment for a heart attack begins. The prior art has attempted to address this need by providing patient monitors and defibrillators that have some communication features so that medical help can be sought more quickly. For example, Reinhold, Jr. et al. U.S. Pat. No. 4,531,527 describes a cardiac monitoring system in which patient units mounted on patients collect and analyze patient ECG information. The patient units thereafter transmit the collected and analyzed information telephonically to a remote office unit. The office unit can then transmit the information to a physician.
Christ et al. U.S. Pat. No. 5,228,449 describes a system for detecting out-of-hospital cardiac emergencies and summoning emergency assistance. A wrist-mounted monitor detects a patient's pulse through use of infrared photoplethysmography and sends RF signals to a base unit. If the patient suffers a cardiac arrest, an alarm will sound in both the wrist unit and the base unit. The base unit will automatically connect to a telephone line to dial for assistance. The device also has a removable instructions player that provides CPR instructions to anyone assisting the heart attack victim.
Gessman U.S. Pat. No. 4,102,332 describes a portable defibrillator with a pre-programmed dialer that telephones a physician when activated by the user, i.e., the patient or attending caregiver. While the physician and the patient and/or attending caregiver communicate with each other via the defibrillator's communication system, the physician alone controls operation of the defibrillator from his or her remote location. During use, the defibrillator sends operation and status data to the physician.
Adams et al. U.S. Pat. No. 5,336,245 describes an interrogator for an implanted defibrillator. The interrogator communicates with the implanted defibrillator via RF signals. The interrogator communicates with a nearby modem via RF, IR, or over a hard wire. The modem, in turn, sends defibrillator data via telephone lines to a physician's office. The physician can also control operation of the interrogator remotely and can send information to the patient for display on the interrogator display.
Heilman U.S. Pat. No. 5,078,134 describes an automatic external defibrillator mounted in a belt on a patient. The defibrillator transmits patient data via RF with a separate "maintenance unit." The maintenance unit communicates telephonically with a physician via a modem, dialer and speakerphone when a user depresses a button to dial the physician.
The disclosures of the patents cited above are incorporated herein by reference.